Question 10: An incompressible liquid is passed through a horizontal pipe and it is observed that the speed of mass of liquid when emerges is greater than the speed when it enters the pipe. How can it be possible?
We know from the equation of continuity that,
Where A1 and A2 are the cross-sectional areas of the pipe where the incompressible fluid enters and emerges, respectively. v1 and v2 are the respective velocities of the incompressible fluid at these points.
Now from the above equation,
This means the emerging velocity v2 is times the entering velocity v1.
Now if v2 > v1 ⇒ > 1 ⇒ A1 > A2.
So if the emerging velocity of the fluid is greater than the entering velocity, this means that the cross-section of the pipe at the entering point of the fluid is greater than the cross-section of the pipe where the fluid emerges out.